Method and apparatus in a wireless communications system

ABSTRACT

A method in a user equipment for requesting that a base station schedule the user equipment for an uplink data transmission to the base station is provided. The user equipment comprises a buffer. Directly or indirectly responsive to receiving data into the buffer to be transmitted to the base station, the user equipment generates a scheduling request trigger. The scheduling request trigger is configured to trigger the sending of a scheduling request to the base station if the trigger is pending at the next scheduling request opportunity, and to remain pending until it is cancelled. The user equipment cancels the pending scheduling request trigger when the data is accounted for in a buffer status report, which reports the size of the buffer to the base station, or when the data is included directly in a scheduled uplink data transmission whichever occurs first.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/537,202 filed Nov. 10, 2014, which is a continuation of U.S. patentapplication Ser. No. 12/717,176 filed 4 Mar. 2010, which claimedpriority under 35 U.S.C. §119(e) from U.S. Provisional Application No.61/175,668, filed on 5 May 2009, also claimed priority under 35 U.S.C.§365(c) from International Application No. PCT/SE2010/050063, filed on25 Jan. 2010. The disclosures of each of these applications areincorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a method and an apparatus in a userequipment. In particular, it relates to handling scheduling requesttriggers.

BACKGROUND

In a typical cellular radio system, also referred to as a wirelesscommunication system, User Equipments (UEs) communicate via a RadioAccess Network (RAN) to one or more core networks. The user equipmentsmay also be known as mobile terminals and/or wireless terminals. Inparticular, the user equipments may be mobile stations or user equipmentunits, such as mobile telephones (e.g., “cellular” telephones), andlaptops with wireless capability (e.g., mobile termination). Userequipments may therefore be portable, pocket, hand-held,computer-included, or car-mounted mobile devices which communicate voiceand/or data with the radio access network.

The radio access network covers a geographical area which is dividedinto cell areas, with each cell area being served by a base station,e.g., a Radio Base Station (RBS), which in some networks is also called“eNB”, “NodeB” or “B node” and which in this document is referred to asa base station. A cell is a geographical area where radio coverage isprovided by the radio base station equipment at a base station site. Thebase stations communicate over the air interface, operating on radiofrequencies, with user equipment units that are within range of the basestations.

In wireless communication systems, the radio UpLink (UL) is thetransmission path from the user equipment to a base station and theradio DownLink (DL) is the transmission path from a base station to theuser equipment. In Release 8, of the 3GPP Long Term Evolution (LTE)standard, the arrival of new UL data of higher priority than the alreadyexisting data, or of any priority when there is no previous data, to theUE buffer triggers a so-called Regular Buffer Status Report (BSR). Thereare, of course, side conditions to this. For example, new UL data onlytriggers a BSR if it is data for a logical channel belonging to aLogical Channel Group (LCG). Further, the “arrival of new UL data” isdefined as when UL data becomes available for transmission in a RadioLink Controller (RLC) entity, or in the Packet Data Convergence Protocol(PDCP) entity. The PDCP is an upper layer of the RLC entity

However, notwithstanding these side conditions, the arrival of new ULdata generally triggers a regular BSR. The regular BSR, in turn,triggers the generation of a Scheduling Request (SR) trigger. The SRtrigger then triggers an SR to be conveyed to the base station, therebyinforming the base station that the user equipment has new data that itwould like to transmit. The SR is transmitted to the base station eitheron (1) the user equipment's preallocated scheduling request resource ona Physical Uplink Control Channel (PUCCH), in which case the SR is knownas dedicated SR (D-SR) since it is transmitted on a resource dedicatedto the user equipment, or (2) on the Physical Random Access Channel(PRACH), in which case the SR is known as a random access SR (RA-SR). Inboth cases, there is a fixed periodicity associated with theopportunities to transmit an SR. This means that, in order to transmitan SR, the user equipment has to wait until such an opportunity isavailable.

When the base station receives a D-SR, the base station typically issuesan UL grant. When the user equipment transmits on that grant, it willtransmit a MAC Packet Data Unit (PDU) that includes a BSR in the shapeof a so-called BSR Medium Access Control (MAC) control element,describing the size of its buffers. The BSR is mandated to reflect thebuffer status after the MAC PDU, including the BSR MAC control element,is built. A BSR is always included if a BSR trigger is pending in theuser equipment at the time of building the MAC PDU, unless all data canfit in the MAC PDU but there is not room enough for a BSR in addition tothe data.

Once the size of the user equipment buffer has been reported to the basestation, there is no need for the user equipment to send additional SRsas the base station now knows how much data the user equipment has totransmit. The SR trigger can hence be cancelled in the user equipment,so that the user equipment will not send any D-SR at the next D-SRopportunity.

Please note that in the description below, the following terminologywill be used:

The term “arrival of new data” is used to indicate arrival of new ULdata in the user equipment buffer, with all side conditions fortriggering a Regular BSR satisfied.

The term “reception of grant” is used to indicate the reception of aPhysical Downlink Control Channel (PDCCH) grant for Uplink SharedChannel (UL-SCH) resources for a new transmission.

The term “transmission of data” is used to indicate transmission of ULdata on UL-SCH resources that have been made available for a newtransmission.

The term “SR” and “scheduling request” is used to indicate signalling ofD-SR on the PUCCH.

The term “SR trigger” and “scheduling request trigger” is used toindicate a pending SR.

When expressions such as “buffer status report accounts for first data”are used, it means that the buffer status report reflects whatever isleft of the first data after the transmission in which the buffer statusreport is included has been received.

An SR is considered pending until cancelled, i.e. an SR trigger thattriggers the transmission of an SR, is considered pending untilcancelled. It was first agree upon, in a prior version of the LTEstandard, that an SR would be cancelled in the first possibleTransmission Time Interval (TTI), also known as subframe, when UL-SCHresources for a new transmission are granted. However, some argued thatit was unclear exactly when UL-SCH resources for a new transmission aregranted, whether it be when a PDCCH grant is received or in the TTI whenthe UL-SCH resources are actually available. It was subsequently agreedupon that all pending SRs should be cancelled in the TTI when UL-SCHresources are actually available for a new transmission.

SUMMARY

Embodiments of the present disclosure improve the performance of awireless communications network.

One embodiment, for example, comprises a method in a user equipment forrequesting that a base station schedule the user equipment for an uplinkdata transmission to the base station. The user equipment comprises abuffer. The method includes receiving data into the buffer that is to betransmitted to the base station via a scheduled uplink datatransmission. The method then includes sending a scheduling request tothe base station when a next scheduling request opportunity occurs, ifand only if the buffer comprises data that has neither been accountedfor in a buffer status report, which reports the size of the buffer tothe base station, or included directly in a scheduled uplink datatransmission

In another embodiment, the user equipment generates a scheduling requesttrigger after receiving data into the buffer to be transmitted to thebase station. The scheduling request trigger is triggered directly orindirectly by the arrived data; that is, the user equipment generatesthe scheduling request trigger directly, or indirectly, responsive tothe arrival of such data. The scheduling request trigger is configuredto trigger the sending of a scheduling request to the base station ifthe trigger is pending at the next scheduling request opportunity. Oncegenerated, the scheduling request trigger remains pending until it iscancelled by the user equipment. The user equipment cancels the pendingscheduling request trigger when the data is accounted for in a bufferstatus report, or when that data is included directly in a scheduleduplink data transmission, whichever occurs first.

According to yet another embodiment, the user equipment tracks what datain the buffer has been accounted for in a buffer status report and whatdata in the buffer has been included directly in a scheduled uplink datatransmission. The user equipment also tracks what data has not beenaccounted for in a buffer status report or included directly in ascheduled uplink data transmission.

Various embodiments of the present disclosure likewise include a userequipment configured with one or more circuits for performing the abovemethods.

Regardless, each embodiment of the present disclosure advantageouslysends a scheduling request only when necessary. For example, manyembodiments cancel the sending of a pending scheduling request when ithas served its purpose. This is only guaranteed if the schedulingrequest is cancelled when the data that triggered it is accounted for ina buffer status, or the data that triggered it is included in ascheduled transmission. Thereby the performance in the wirelesscommunications network improves by making sure no scheduling requestsare sent unnecessarily and no scheduling requests are cancellederroneously. Unnecessarily sent scheduling requests lead to increasedinterference and potentially to unnecessary grants for Uplink SharedChannel resources being sent by the base station, and erroneouslycancelled scheduling requests can lead to the user equipment not beingable to transmit data in its buffer.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is described in more detail with reference toattached drawings illustrating exemplary embodiments in which:

FIG. 1 is a schematic diagram illustrating an analysis of the problemaddressed by various embodiments of the present disclosure.

FIG. 2 is a schematic diagram illustrating an analysis of the problemaddressed by various embodiments of the present disclosure.

FIG. 3 is a schematic diagram illustrating an analysis of the problemaddressed by various embodiments of the present disclosure.

FIG. 4 is a schematic block diagram illustrating a wirelesscommunication network according to one embodiment of the presentdisclosure.

FIG. 5 is a flowchart depicting a method according to one embodiment ofthe present disclosure.

FIG. 6 is a schematic diagram illustrating an analysis of variousembodiments of the present disclosure.

FIG. 7 is a schematic diagram illustrating an analysis of variousembodiments of the present disclosure.

FIG. 8 is a schematic diagram illustrating an analysis of variousembodiments of the present disclosure.

FIG. 9 is a schematic block diagram illustrating a user equipmentaccording to one embodiment of the present disclosure.

FIG. 10 is a schematic block diagram illustrating a user equipmentaccording to one embodiment of the present disclosure.

DETAILED DESCRIPTION

As mentioned above, the latest version of the LTE standard specifiesthat all pending SRs shall be canceled in the TTI when UL-SCH resourcesare actually available for a new transmission. FIG. 1 illustrates ananalysis of this alternative in the case that new, second data arrivesto the user equipment buffer before a grant for the first data isreceived. That is, assume that first data has arrived to the userequipment buffer. This first data has triggered a buffer status report.This first data has also directly or indirectly triggered a firstscheduling request trigger, for sending a scheduling request at the nextscheduling request opportunity. The scheduling request opportunity hasoccurred and a first scheduling request has been transmitted to the basestation. The first scheduling request trigger is still pending. It willbe cancelled upon transmission of UL data; that is, in the TTI whenUL-SCH resources are actually available for transmitting that UL data.

Looking at a time line, there are then two different cases that appear,case a) and case b) illustrated in FIG. 1. In case a), the userequipment has a scheduling request opportunity between receiving the ULgrant and transmitting the data. In case b) the user equipment has noscheduling request opportunity between receiving the UL grant andtransmitting the data; the next SR opportunity occurs after thetransmission of the data.

For case a) assume the following steps:

Step 100.

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report trigger. This second data, directly orindirectly via the buffer status report trigger, also triggers a secondscheduling request trigger to send a scheduling request for the seconddata at the next opportunity.

Step 110.

As a response to the first scheduling request sent to the base station,the user equipment receives from the base station, an UL grant fortransmission.

Step 115.

The first and second scheduling request triggers are pending, implyingthat the user equipment will send a scheduling request to the basestation at the next scheduling request opportunity. At this point intime a scheduling request opportunity occurs, i.e., this schedulingrequest opportunity occurs between receiving the UL grant andtransmitting the data according to case a). Therefore the user equipmentagain sends a scheduling request to the base station although a granthas already been received. This is unnecessary to send and is confusingfor the base station to receive. This is a disadvantage.

Step 120.

In this step the user equipment transmits to the base station. It cannotbe known for sure if the user equipment transmission includes data fromthe first or second data since the grant is just a grant of resourcesand the user equipment makes the decision of which data to transmit. Thesecond data may be of higher priority than the first data, in which caseparts of second data will be sent. However, a buffer status report isalso included in the transmission to the base station, unless all datacan fit in the transmission but not a buffer status report. If included,the buffer status report accounts for whatever is left of the first dataand also for the second data after the scheduled transmission has beenmade. Since the rule in this example is to cancel SR at transmission ofUL data, the user equipment cancels both pending SR triggers at thispoint in time. However, the base station does not know how to interpretthe second scheduling request 115. Based on the second schedulingrequest, it may send a new grant thinking there is more data that hasnot been accounted for in the transmission (120). If the buffer statusreport sent in the transmission (120) reflects empty buffers, such a newgrant will only be filled by transmitting padding bits, meaning thatboth the grant and the padding transmission were unnecessary, takingresources that could have been used for other user equipments.

For case b) there are fewer problems. Assume the following steps:

Step 100.

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report trigger. This second data, directly orindirectly via the buffer status report trigger, also triggers a secondscheduling request trigger to send a scheduling request for the seconddata at the next opportunity.

Step 110.

As a response to the first scheduling request sent to the base station,the user equipment receives from the base station, an UL grant fortransmission.

Step 120.

The user equipment transmits to the base station. Again, it cannot beknown for sure if the user equipment transmission includes data from thefirst or second data. A buffer status report is included in thetransmission to the base station, which buffer status report accountsfor the first data and also for the second data since the second dataarrived before the grant. Since the rule in this example is to cancelscheduling request at transmission of UL data, the user equipmentcancels both pending scheduling request triggers at this point in time.This is good since no further scheduling requests need to be sent.

Step 125.

A scheduling request opportunity occurs at this point in time, i.e.after the transmission of the data according to case b). The userequipment had no scheduling request opportunity between receiving the ULgrant and transmitting the data as in case a). The scheduling requesttriggers are canceled and therefore not pending any more. This meansthat the user equipment will not again send a scheduling request to thebase station at this next scheduling request opportunity. It is OK thatthe scheduling request was cancelled at the transmission. Since thesecond data arrived before the grant, it is assured that the second datais accounted for in the buffer status report or fully included in thetransmission. That is good and safe.

In case a), the scheduling request trigger has not yet been cancelledwhen the scheduling request opportunity occurs. Hence, a new schedulingrequest is sent, although the user equipment has already received agrant in response to its previous scheduling request. There is no needfor the second scheduling request in this case, but the user equipmentis mandated by the specification to send it. This is a waste of userequipment energy and of radio resources, since the scheduling requestcreates unnecessary interference on the Physical Uplink Control Channel(PUCCH). Additionally, it is not clear what the base station should doin response to the unnecessary scheduling request. Note that the sameprocedure, with an extra unnecessary scheduling request and its unwantedconsequences, would happen in case a) even if the user equipmentreceived the first data but no second data.

However, there is an even more complicated case with worse problems inthe following example related to FIGS. 2 and 3, where the user equipmentgets new data to its buffer after a grant corresponding to the firstscheduling request is received. This new data triggers a schedulingrequest trigger. Looking at a time line, there are then two differentcases that appear, case a) illustrated in FIG. 2 and case b) illustratedin FIG. 3. In this example, as in the example in case a) relating toFIG. 1, the user equipment has a scheduling request opportunity betweenreceiving the UL grant and transmitting the data. In case b) the userequipment has no scheduling request opportunity between receiving the ULgrant and transmitting the data; the next scheduling request opportunityoccurs after the transmission of the data.

In case a) and in case b) there are two respective alternatives,alternative I and alternative II. FIG. 2 depicts case a) alternative Iand case a) alternative II, and FIG. 3 depicts case b) alternative I andcase b) alternative II.

Hence, FIG. 2 illustrates an analysis of the alternative to a cancel SRat transmission of UL data, when new data arrives between reception ofgrant and transmission of data corresponding to the grant for case a),wherein the user equipment has an SR opportunity between receiving theUL grant and transmitting the data. For example, assume that first datahas arrived to the user equipment buffer. This first data has triggereda buffer status report trigger. This first data has also, directly orindirectly via the buffer status report trigger, triggered a firstscheduling request trigger, for sending a scheduling request at the nextscheduling request opportunity. The SR opportunity has occurred and thefirst scheduling request has been transmitted to the base station. Thefirst scheduling request trigger has not yet been cancelled, however, istherefore still pending. It will be cancelled upon transmission of ULdata.

For case a-I) assume the following steps:

Step 200 Case a-I).

As a response to the SR sent to the base station, the user equipmentreceives from the base station an UL grant for transmission.

Step 210 Case a-I).

During a time period the user equipment builds a packet data unit, suchas a MAC PDU, for parts or all of the first data to be transmitted in,and includes a buffer status report in the packet data unit (unless alldata can fit in but not a buffer status report). This packet data unitshall be sent to the base station at the transmission later on. Thebuffer status report accounts only for the first data.

Step 220 Case a-I).

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report. This second data further, directly orindirectly via the buffer status report trigger, triggers a secondscheduling request trigger to send a scheduling request at the nextopportunity. The second scheduling request trigger is pending inaddition to the first scheduling request trigger, triggered by the firstand the second data, respectively.

Step 240 Case a-I).

At this point in time a scheduling request opportunity occurs, i.e.,this scheduling request opportunity occurs between receiving the ULgrant and transmitting the data according to case a). Therefore the userequipment sends a second scheduling request to the base station, sincethe scheduling request has not yet been cancelled. This is necessary asthe user equipment has already built the packet data unit includingparts or all of the first data to be sent, before the second data becameavailable in the user equipment buffer. The second data is thereby notaccounted for in the buffer status report which will be sent at thetransmission.

Step 250 Case a-I).

The user equipment transmits the packet data unit including the bufferstatus report, which buffer status report was triggered by the firstdata (mentioned above) and which buffer status report accounts for thefirst data but not the second data. Since the rule in this example is tocancel a scheduling request at transmission of UL data, the userequipment cancels both pending scheduling request triggers at this pointin time. At this point, it is difficult for the base station to know howto interpret the second scheduling request sent; it does not know if thesecond scheduling request corresponds to second data, or if itcorresponds to the first data, whose scheduling request trigger had notyet been cancelled. If the base station does not send a grant, it risksleaving the user equipment with data in its buffer, unable to transmit,and if it does send a new grant, it risks that this grant wasunnecessary and the corresponding transmission will only be padding.Additionally, if the second scheduling request is not heard by the basestation, e.g. because of excessive interference on PUCCH or PUCCHcoverage problems, the scheduling request triggers are now cancelled andno new scheduling request will be sent even if no new grant is receivedfor the second data. This means that the user equipment cannot get agrant from the base station to transmit its second data, which willremain in the user equipment since the base station does not know of itsexistence.

For case a-II) assume the following steps:

Step 200 Case a-II).

As a response to the first scheduling request sent to the base station,the user equipment receives from the base station, an UL grant fortransmission.

Step 220 Case a-II).

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report trigger. This second data further,directly or indirectly via the buffer status report trigger, triggers asecond scheduling request trigger, to send a scheduling request at thenext opportunity. In case a-II), the second data arrives before buildingthe packet data unit, whereas in case a-I the second data arrived afterbuilding the packet data unit.

Step 230 Case a-II).

During a time period the user equipment builds a packet data unit, suchas a MAC PDU, for data to be transmitted in, which data is built in thepacket data unit depending on the priority of the data in user equipmentbuffer. The user equipment includes a buffer status report in the packetdata unit (unless all data can fit in but not a buffer status report).This packet data unit shall be sent to the base station at thetransmission later on. The buffer status report accounts for both thefirst data and the second data.

Step 240 Case a-II).

The first and second scheduling request triggers are pending. At thispoint in time a scheduling request opportunity occurs, i.e., thisscheduling request opportunity occurs between receiving the UL grant andtransmitting the data according to case a). Therefore the user equipmentagain sends a scheduling request to the base station, since bothscheduling request triggers are not yet cancelled. Just as in FIG. 1a ,this is unnecessary, since both first and second data will be includedin the buffer status report sent on already allocated resources.

Step 250 Case a-II).

The user equipment transmits data and the buffer status report in thebuilt packet data unit, which buffer status report accounts for thefirst data and the second data. Since the rule in this example is tocancel scheduling request at transmission of UL data, the user equipmentcancels both pending scheduling request triggers at this point in time.

In both case a-I and case a-II, an extra scheduling request is sent.Moreover, when receiving the extra scheduling request, the base stationonly knows that it has received two scheduling requests and thereforecannot distinguish between case a-I and case a-II, i.e. the base stationcannot determine whether the same data was behind both schedulingrequests, or if additional data was received for the second schedulingrequest. Correspondingly, the base station does not know if the bufferstatus report it received actually reflects the user equipment buffersizes, as new data could have arrived after the buffer status report wasbuilt. The base station hence has to guess, and depending on its guessit risks either wasting a grant or losing track of the new data (since,because the new data has not been reported, the base station would havean inaccurate buffer size estimation).

FIG. 3 illustrates an analysis of the alternative to cancel a schedulingrequest at transmission of UL data, when new data arrives betweenreception of grant and transmission of data corresponding to the grantfor case b), wherein the user equipment has no scheduling requestopportunity between receiving the UL grant and transmitting the data;the next scheduling request opportunity occurs after the transmission ofthe data. Assume, for instance, that first data has arrived to the userequipment buffer. This first data has triggered a buffer status reporttrigger. This first data also, directly or indirectly via the bufferstatus report trigger, has triggered a first scheduling request trigger,for sending a scheduling request at the next scheduling requestopportunity. The scheduling request opportunity has occurred and thefirst scheduling request has therefore been transmitted to the basestation. The first scheduling request trigger has not yet beencancelled, and is therefore still pending. It will be cancelled upontransmission of UL data.

For case b-I) assume the following steps:

Step 300 Case b-I).

As a response to the scheduling request sent to the base station, theuser equipment receives from the base station an UL grant fortransmission.

Step 310 Case b-I).

During a time period the user equipment builds a packet data unit, suchas a MAC PDU, for parts or all of the first data to be transmitted in,and includes a buffer status report in the packet data unit (unless alldata can fit in but not a buffer status report). The packet data unitshall be sent to the base station at the transmission later on. Thebuffer status report accounts only for the first data.

Step 320 Case b-I).

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report. This second data further, directly orindirectly via the buffer status report trigger, triggers a secondscheduling request trigger to send a scheduling request at the nextopportunity.

Step 340 Case b-I).

The user equipment transmits the first data built in the packet dataunit and includes the buffer status report in the packet data unit,which buffer status report was triggered by the first data and whichbuffer status report accounts for the first data but not the seconddata. Since the rule in this example is to cancel a scheduling requestat transmission of UL data, the user equipment cancels both pendingscheduling request triggers at this point in time. This means that thereis no longer any pending scheduling request triggers to indicate thatthere is second data in the user buffer, even though no schedulingrequest for the second data has been transmitted to the base stationyet, since no scheduling request opportunity has appeared at this pointin time. In this case, the scheduling request needed for the second datawill be lost!

Step 350 Case b-I).

At this point in time a scheduling request opportunity occurs i.e. afterthe transmission of the data according to case b). No scheduling requesttrigger is pending since it was cancelled in step 340. So as mentionedabove, in this case, the SR for the second data will be lost. This isnot good.

For case b-II) assume the following steps:

Step 300 Case b-II).

As a response to the scheduling request sent to the base station, theuser equipment receives from the base station an UL grant fortransmission.

Step 320 Case b-II).

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report trigger. This second data further,directly or indirectly, triggers a second scheduling request trigger, tosend a scheduling request at the next opportunity. Thus in case b-II),the second data arrives before building the packet data unit, whereas incase b-I) the second data arrived after building the packet data unit.

Step 330 Case b-II).

During a time period the user equipment builds a packet data unit, suchas a MAC PDU, for data to be transmitted in, which data is built in thepacket data unit depending on the priority of the data in the userequipment buffer. The user equipment includes a buffer status report inthe packet data unit (unless all data can fit in but not a buffer statusreport). This packet data unit shall be sent to the base station at thetransmission later on. The buffer status report accounts for both thefirst data and the second data.

Step 340 Case b-II).

The user equipment transmits the data and the buffer status report inthe packet data unit, which buffer status report accounts for the firstdata and the second data. Since the rule in this example is to cancel SRat transmission of UL data, the user equipment cancels the pending SRtrigger at this point in time.

Step 350 Case b-II).

At this point in time, an SR opportunity occurs i.e. after thetransmission of the data according to case b). No SR trigger is pendingsince it was cancelled in step 340. This is good in this case, sincefirst and second data are already transmitted or accounted for in theBSR.

As can be seen, case b-II) works well but case b-I) does not. In bothcases, the triggered second scheduling request trigger is never sent asit is cancelled when the first data is transmitted. However, if thesecond data is not included in the buffer status report sent as in caseb-I), the base station will not know about this data. Two things maysave the situation: (1) the user equipment receiving a grant for otherdata, not in response to the scheduling request never sent, since thetransmission on that grant will include a buffer status report, or (2) anew SR being triggered by the arrival of yet new data.

Unless one of these occurs, the user equipment has no means of sending anew scheduling request until the fallback mechanism known as “retransmitbuffer status report timer” or “retx-BSR-Timer” expires, triggering ascheduling request. However, this timer has a minimum value of 320 mswhich adds considerable delay.

Therefore it is an object of the present disclosure to provide amechanism in a user equipment that improves the performance in thewireless communications network.

Referring now to one embodiment of the present disclosure, FIG. 4depicts a wireless communications system 100. The wirelesscommunications system 100 is a packet-based communications system, whichmay be an LTE communications system, Worldwide Interoperability forMicrowave Access (WiMax) system, or any other wireless communicationssystem handling scheduling requests for uplink scheduling.

The wireless communications system 100 comprises a base station 110serving a cell 115. The base station 110 is a radio base station such asan eNB, a Radio Base Station (RBS) or any other network unit capable ofcommunicating over a radio carrier with user equipments being present inthe cell.

A user equipment 120 being present within the cell 115, is served by thebase station 110, and is therefore capable of transmitting data packetunits such as MAC PDUs to the base station 110 over a radio channel 125.The user equipment 120 may be a terminal, e.g. a mobile terminal or awireless terminal, a mobile phone, a computer such as e.g. a laptop,Personal Digital Assistants (PDA), or any other radio network unitscapable to communicate with a base station over an air interface. Theair interface may e.g. be an E-UTRA air interface used in LTE.

The user equipment 120 comprises a buffer, to which buffer new uplinkdata arrives that is to be transmitted to the base station 110. The datamay be voice data, video data, photo data, text data or any other kindof data that a user may want to transmit. The arrival of new UL data ofhigher priority than the already existing data, or of any priority whenthere is no previous data, to the user equipment buffer triggers abuffer status report. The arrived new data further directly orindirectly triggers a scheduling request trigger to be pending. Theindirectly triggering may be performed such that the arrived datatriggers a buffer status report which in turn triggers the schedulingrequest trigger. The scheduling request trigger will trigger ascheduling request to be sent to the base station 110 at a nextscheduling request opportunity. The “scheduling request trigger” mayalso be referred to as “a pending scheduling request”. As mentionedabove there is a fixed periodicity associated with the opportunities totransmit scheduling requests to the base station 110, so the userequipment 120 has to wait until such an opportunity is available. Thebase station 110 receiving the scheduling request is in that wayinformed that the user equipment 120 has new data that it would like totransmit. A scheduling request trigger is pending or not pending. Ascheduling request is typically not associated with any specific arriveddata and a scheduling request trigger does not need to be associatedwith any data, although it is implicitly associated with the data thattriggered it. But if further data, here called second data, arrives tothe user equipment buffer, thereby triggering a scheduling requesttrigger, a further scheduling request is triggered, even if a schedulingrequest trigger is already triggered.

As a response to a scheduling request, the base station 110 typicallysends an uplink grant to the user equipment 120. The grant is specificto a user equipment, but is not associated with any specific arriveddata in that user equipment. Priorities set by the eNB and signalled tothe user equipment 120 decides which particular data shall betransmitted on the resources that the user equipment 120 has beenallocated.

To make the handling of the scheduling procedure more reliable, whichwill improve the performance in the wireless communications network, apending scheduling request trigger is cancelled in accordance with oneembodiment as follows:

In a first embodiment, the pending scheduling request is cancelled whenthe data that triggered the scheduling request is accounted for in abuffer status report to be included in a scheduled data transmission tobe transmitted to the base station 110, or when the data that triggeredthe scheduling request is included in a scheduled data transmission tobe transmitted to the base station, whichever occurs first. In thislatter case, the scheduled data need not be transmitted, just includedin the packet data unit that a bit later will be transmitted.

Alternatively, in a second embodiment, the pending scheduling request iscancelled at any time by the user equipment, but the user equipment 120keeps track of what data has been accounted for in the buffer statusreport to be included in a scheduled data transmission and what data hasnot been accounted for. In this case, when a next scheduling requestopportunity appears, the user equipment 120 sends a scheduling requestif and only if the buffer comprises data that has not yet been accountedfor in a buffer status report. This is equivalent to having a pendingscheduling request in the first embodiment, but does not necessarilyhave to be called “having a pending scheduling request”. The consequencewill however be the same: at the next scheduling request opportunity,the user equipment 120 will send a scheduling request if there is datanot yet included in a buffer status report, and that data has not yetbeen sent.

A method in the user equipment 120 for handling a scheduling requesttrigger, according to some embodiments, will now be described withreference to the flowchart depicted in FIG. 5. As mentioned above, theuser equipment 120 comprising a buffer.

The method comprises the following steps, which steps may as well becarried out in another suitable order than described below:

Step 501

The buffer in the user equipment 120 receives data to be transmitted toa base station 110.

Step 502

This step is optional, according to some embodiments, the user equipment120 generates a buffer status report trigger. The buffer status reporttrigger is triggered by the arrived data.

Step 503

The user equipment 120 generates a scheduling request trigger, whichscheduling request trigger is pending until it is cancelled, and whichgeneration is triggered directly or indirectly by the arrived data. Insome embodiments where this step is performed indirectly, the generationis triggered by the generation of the buffer status report trigger,which in turn was triggered by the arrived data.

Step 504

According to a first embodiment, the user equipment 120 cancels thepending scheduling request when the data that triggered the schedulingrequest is accounted for in a buffer status report to be included in ascheduled data transmission to be transmitted to the base station 110,or the user equipment 120 cancels the pending scheduling request whenthe data that triggered the scheduling request is included in ascheduled data transmission to be transmitted to the base station,whichever occurs first. The pending scheduling request trigger may hencebe cancelled at the same time instance during which the MAC PDUincluding a buffer status report MAC control element is built.

When a packet data unit such as a MAC PDU is built, it includes a bufferstatus report such as a BSR MAC control element. The buffer statusreport accounts for data remaining in the user equipment buffer afterthe building of the packet data unit. Such a buffer status report isincluded if a buffer status report trigger is pending at the time thatthe MAC PDU is built, and all data cannot fit in the MAC PDU.

The user equipment 120 may cancel the pending scheduling request whenthe data that triggered the scheduling request is included in the bufferstatus report represented by a BSR MAC control element or when all datathat triggered the scheduling request has been included in a MAC PDU fortransmission. In the context of the LTE standards, such a method ofoperation can be understood as the user equipment 120 canceling apending scheduling request when the buffer status report that triggeredthe scheduling request is canceled. Here, “when” does not necessarilyconnote a coincidence in time, and can be understood as the pendingscheduling request being canceled upon cancellation of the pendingbuffer status report that triggered the pending scheduling request. Inother words, in at least one embodiment, a pending scheduling requesttrigger is canceled, e.g. along with canceling the corresponding bufferstatus report trigger, if a currently scheduled data transmission willinclude all of the new data that caused the corresponding buffer statusreport trigger to be generated, or if a buffer status report to beincluded in the next currently scheduled data transmission—which mayhave been generated because of one or more other pending buffer statusreport triggers—will account for the new data.

Step 505

According to a second embodiment, as an alternative to step 504, theuser equipment 120 cancels the pending scheduling request at any time,but the user equipment 120 keeps track of what data has been accountedfor in the buffer status report to be included in a scheduled datatransmission and what data has not been accounted for, and according tosome embodiments, nor been included in a scheduled data transmission.

Step 506

According to the second embodiment, when a next scheduling requestopportunity appears, the user equipment 120 sends a scheduling requestif and only if the buffer comprises data that has not yet been accountedfor in the buffer status report.

In this alternative embodiment, the user equipment 120 may internallycancel its pending scheduling request trigger whenever it wants, beforeor after the point in time in which the user equipment would havecancelled it according to the first embodiment in step 504, while stillfulfilling the behaviour that can be tested by the 3GPP. This is, asmentioned above, performed by the user equipment 120 keeping track ofdata that has not yet been included in a buffer status report, andaccording to some embodiments, nor been included in a scheduled UL datatransmission. This is equivalent to having a pending scheduling requestin the first embodiment, but does not necessarily have to be called“having a pending scheduling request”. The consequence will however bethe same, at the next scheduling request opportunity, the user equipment120 will send a scheduling request if there is data not yet included ina buffer status report, and that data has not yet been sent.

Further, in some embodiments as mentioned above, the buffer statusreport trigger may be generated in response to new data incoming to anuplink transmit buffer, and a scheduling request trigger may begenerated corresponding to the buffer status report trigger. Thus,receiving new data into the uplink transmit buffer causes a new bufferstatus report trigger to be generated, which causes a new schedulingrequest trigger.

In one or more embodiments taught herein, advantageous handling andcancelling of pending buffer status report triggers and correspondingpending scheduling request triggers prevents uplink data from becomingstuck in the user equipment 120, and/or prevents or at least reducesunnecessary scheduling request transmissions and resultant unnecessaryuplink resource grants.

Those skilled in the art will also appreciate that buffer status reporttriggers and corresponding scheduling request triggers may beimplemented as flags or other logical indicators, which may be set orotherwise created to indicate the pending status, and cleared orotherwise deleted for cancellation.

FIG. 6 illustrates an analysis according to the first embodiment, whennew second data arrives to the user equipment buffer before a grant forthe first data is received, i.e., the first embodiment comprisescancelling the scheduling request trigger when the data that triggeredthe scheduling request is accounted for in a buffer status report to beincluded in a scheduled data transmission to be transmitted to the basestation 110, or cancelling the pending scheduling request when the datathat triggered the scheduling request is included in a scheduled datatransmission to be transmitted to the base station, whichever occursfirst. Assume again that first data has arrived to the user equipmentbuffer, which corresponds to step 501 in FIG. 5. This first data hastriggered a buffer status report, which corresponds to step 502 in FIG.5. This first data has also directly or indirectly triggered a firstscheduling request trigger, for sending a scheduling request at the nextscheduling request opportunity, which corresponds to step 503 in FIG. 5.The scheduling request opportunity has occurred and the first schedulingrequest has been transmitted to the base station 110. The firstscheduling request trigger is still pending. Looking at a time line,there are then two different cases that appears, case a) and b)illustrated in FIG. 6. In case a), the user equipment 120 has ascheduling request opportunity between receiving the UL grant andtransmitting the data. In case b) the user equipment 120 has noscheduling request opportunity between receiving the UL grant andtransmitting the data; the next scheduling request opportunity occursafter the transmission of the data.

For case a) assume the following steps:

Step 600.

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report. This second data directly or indirectlyvia the buffer status report trigger, triggers a second schedulingrequest trigger to send a scheduling request at the next opportunity.

Step 610.

As a response to the first scheduling request sent to the base station110, the user equipment 120 receives an UL grant for transmission fromthe base station 110.

Step 612.

During a time period the user equipment 120 builds a packet data unit,such as a MAC PDU, for parts or all of the first and second data to betransmitted in, and includes a buffer status report in the packet dataunit (unless all data can fit in but not a buffer status report). Thepacket data unit shall be sent to the base station 110 at thetransmission later on. According to this embodiment, all pendingscheduling request triggers are canceled at this point in time, and alsoall pending buffer status report triggers.

Step 615.

The first and second scheduling request triggers are not pending,implying that the user equipment 120 will not send a scheduling requestto the base station 110 at the next scheduling request opportunity.Thus, at this point in time when a scheduling request opportunityoccurs, no scheduling request is sent. This is good, since all data hasbeen accounted for either in a buffer status report or in the scheduledtransmission.

Step 620.

The user equipment 120 transmits the built packet data unit to the basestation 110.

For case b) assume the following steps:

Step 600.

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report trigger. This second data directly orindirectly via the buffer status report triggers a scheduling requesttrigger to send a scheduling request at the next opportunity. This stepis the same as for case a).

Step 610.

As a response to the first scheduling request sent to the base station110, the user equipment 120 receives from the base station, an UL grantfor transmission. This step is also the same as for case a).

Step 612.

During a time period the user equipment 120 builds a packet data unit,such as a MAC PDU, for parts or all of the first and second data to betransmitted in, and includes a buffer status report in the packet dataunit (unless all data can fit in but not a buffer status report). Thepacket data unit shall be sent to the base station 110 at thetransmission later on. According to this embodiment, all pendingscheduling request triggers are canceled at this point in time, and alsoall pending buffer status report triggers.

Step 620.

The user equipment 120 transmits the built packet data unit to the basestation 110. Again, it cannot be known for sure if the user equipment120 transmits according to first or second data. A buffer status reportis included in the transmission to the base station 110, which bufferstatus report accounts for the first and also for the second data sincethe second data arrived before the grant. The rule in this example is tocancel the scheduling request trigger when the data that triggered thescheduling request is accounted for in a buffer status report to beincluded in a scheduled data transmission to be transmitted to the basestation 110, or the user equipment 120 cancels the pending schedulingrequest when the data that triggered the scheduling request is includedin a scheduled data transmission to be transmitted to the base station,whichever occurs first. Since this buffer status report and the datapacket unit including first and second data was built before this pointin time of sending, i.e. before step 620, the user equipment 120 hascancelled the pending scheduling request triggers. This is good, sincethere is no reason to send an additional scheduling request at the nextscheduling request opportunity.

Step 625.

A scheduling request opportunity occurs at this point in time, i.e.after the transmission of the data according to case b). The userequipment 120 had no scheduling request opportunity between receivingthe UL grant and transmitting the data as in case a). The schedulingrequest trigger is already canceled and therefore not pending any more.This means that the user equipment 120 will not again send a schedulingrequest to the base station 110 at the next scheduling requestopportunity. This is good.

Hence, no unnecessary scheduling request is sent in either case a) orcase b) and, thus, there is no ambiguity in the user equipment 110 as towhat a scheduling request means. In both cases a) and b), a schedulingrequest means that there is new data in the user equipment 120 that theuser equipment 110 was not previously aware of. There is still an errorcase where the scheduling request opportunity 615 is before the packetunit build 612, in which case there will be an extra scheduling requestsent and an ambiguity in the user equipment 110 as to what the SR meanssimilar to the analysis of case a) in FIG. 1, but there is a muchsmaller probability of having an SR opportunity between arrival ofsecond data and build of packet unit as in the possible error case inFIG. 6, than there is of having an SR opportunity between arrival ofsecond data and transmission of data as in FIG. 1.

FIG. 7 and FIG. 8 illustrates an analysis according to the firstembodiment, where the user equipment 120 gets new data to its bufferafter a grant corresponding to the first scheduling request is received.This new data triggers a scheduling request trigger. Looking at a timeline, there are then two different cases that appears, case a)illustrated in FIG. 7 and b) illustrated in FIG. 8. In case a), the userequipment 120 has a scheduling request opportunity between receiving theUL grant and transmitting the data. In case b) the user equipment 120has no scheduling request opportunity between receiving the UL grant andtransmitting the data, the next scheduling request opportunity comesafter the transmission of the data.

In case a) and in case b) there are two respective alternatives,alternative I and alternative II. FIG. 7 depicts case a) alternative Iand case a) alternative II, and FIG. 8 depicts case b) alternative I andcase b) alternative II.

Hence FIG. 7 illustrates an analysis according to the present embodimentin the scenario when new data arrives between reception of grant andtransmission of data corresponding to the grant for case a), wherein theuser equipment 120 has a scheduling request opportunity betweenreceiving the UL grant and transmitting the data. Assume that first datahas arrived to the user equipment buffer, which corresponds to step 501in FIG. 5. This first data has triggered a buffer status report, whichcorresponds to step 502 in FIG. 5. This first data also, directly orindirectly via the buffer status report trigger, has triggered a firstscheduling request trigger for sending a scheduling request at the nextscheduling request opportunity, which corresponds to step 503 in FIG. 5.The scheduling request opportunity has occurred and the first schedulingrequest has been transmitted to the base station. The first schedulingrequest trigger is still pending. According to this embodiment, thescheduling request trigger will be cancelled when the data thattriggered the scheduling request is accounted for in a buffer statusreport to be included in a scheduled data transmission to be transmittedto the base station 110, or the user equipment 120 cancels the pendingscheduling request when the data that triggered the scheduling requestis included in a scheduled data transmission to be transmitted to thebase station, whichever occurs first.

For case a-I) assume the following steps:

Step 700 Case a-I)

As a response to the scheduling request sent to the base station 110,the user equipment 120 receives from the base station an UL grant fortransmission.

Step 710 Case a-I).

During a time period the user equipment 120 builds a packet data unit,such as a MAC PDU, for parts or all of the first data to be transmittedin, and includes a buffer status report in the packet data unit (unlessall data can fit in but not a buffer status report). This packet dataunit shall be sent to the user equipment 110 at the transmission lateron. The buffer status report accounts for the first data. According tothe first embodiment, the pending first scheduling request is cancelledat this point in time, which corresponds to step 504 in FIG. 5.

Step 720 Case a-I).

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report. This second data further, directly orindirectly, triggers a second scheduling request trigger, to send ascheduling request at the next opportunity. The second schedulingrequest trigger is pending, triggered by the second data.

Step 740 Case a-I).

At this point in time a scheduling request opportunity occurs, i.e. thisscheduling request opportunity occurs between receiving the UL grant andtransmitting the data according to case a). Therefore the user equipment120 sends a second scheduling request to the base station 110, since thesecond scheduling request is pending. This is necessary as the userequipment 120 has already built the packet data unit including parts orall of the first data to be sent, before the second data becameavailable in the user equipment buffer. The second data is thereby notaccounted for in the buffer status report which will be sent to the basestation 110 at the transmission.

Step 750 Case a-I).

The user equipment 120 transmits the packet data unit including thebuffer status report, which buffer status report was triggered by thefirst data (mentioned above) and which buffer status report accounts forthe first data but not the second data. At this point, it is notdifficult any more for the base station 110 to know how to interpret thesecond scheduling request sent, it corresponds to new data not accountedfor in the buffer status report received in the transmission.Additionally, it was necessary for the user equipment 120 to send thesecond scheduling request, since the base station 110 would not haveknown about the second data if the second scheduling request had notbeen sent.

For case a-II) assume the following steps:

Step 700 Case a-II).

As a response to the first scheduling request sent to the base station,the user equipment 120 receives from the base station 110 an UL grantfor transmission.

Step 720 Case a-II).

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report. This second data further, directly orindirectly via the buffer status report, triggers a second schedulingrequest trigger to send a scheduling request at the next opportunity. Incase a-II), the second data arrives before building the packet dataunit, wherein in case a-I) the second data arrived after building thepacket data unit.

Step 730 Case a-II).

During a time period the user equipment 120 builds a packet data unit,such as a MAC PDU, for data to be transmitted in, which data is built inthe packet data unit depending on the priority of the data in the userequipment buffer. The user equipment includes a buffer status report inthe packet data unit (unless all data can fit in but not a buffer statusreport). This packet data unit shall be sent to the base station at thetransmission later on. The buffer status report accounts for the firstand second data being built in the packed data unit. According to thefirst embodiment, the pending first and second scheduling requests arecancelled at this point in time, which corresponds to step 504 in FIG.5.

Step 740 Case a-II).

At this point in time a scheduling request opportunity occurs, i.e. thisscheduling request opportunity occurs between receiving the UL grant andtransmitting the data according to case a). The scheduling requesttriggers are not pending any more. Therefore the user equipment 120 willnot send any scheduling request to the base station 110. This is goodbecause it would have been unnecessary to do so, since both first andsecond data will be accounted for in the buffer status report sent onalready allocated resources.

Step 750 Case a-II).

The user equipment 120 transmits data and the buffer status report inthe built packet data unit, which buffer status report accounts for thefirst data and the second data.

Hence, no unnecessary scheduling request is sent in either case a-I) orcase a-II), and thus there is no ambiguity in the base station 110 as towhat a scheduling request means. In both cases a-I) and a-II), ascheduling request means that there is new data in the user equipment120 that the base station 110 was not previously aware of. The sameerror case as described for FIG. 6 is still present, but with a muchsmaller probability of happening with the present disclosure.

FIG. 8 illustrates an analysis according to one embodiment, in thescenario when new data arrives between reception of grant andtransmission of data corresponding to the grant for case b) wherein theuser equipment 120 has no scheduling request opportunity betweenreceiving the UL grant and transmitting the data, the next schedulingrequest opportunity occurring after the transmission of the data. Assumethat first data has arrived to the user equipment buffer, whichcorresponds to step 501 in FIG. 5. This first data has triggered abuffer status report, which corresponds to step 502 in FIG. 5. Thisfirst data also directly or indirectly via the buffer status reporttrigger, has triggered a first scheduling request trigger for sending ascheduling request at the next scheduling request opportunity, whichcorresponds to step 503 in FIG. 5. The scheduling request opportunityhas occurred and a first scheduling request is transmitted to the basestation. The first scheduling request trigger is still pending.According to one or more embodiments, the scheduling request triggerwill be cancelled when the data that triggered the scheduling request isaccounted for in a buffer status report to be included in a scheduleddata transmission to be transmitted to the base station 110, or the userequipment 120 cancels the pending scheduling request when the data thattriggered the scheduling request is included in a scheduled datatransmission to be transmitted to the base station, whichever occursfirst.

For case b-I) assume the following steps:

Step 800 Case b-I).

As a response to the scheduling request sent to the base station, theuser equipment 120 receives from the base station an UL grant fortransmission.

Step 810 Case b-I).

During a time period the user equipment 120 builds a packet data unit,such as a MAC PDU, for parts or all of the first data to be transmittedin, and includes a buffer status report in the packet data unit (unlessall data can fit in but not a buffer status report). This packet dataunit shall be sent to the user equipment 110 at the transmission lateron. The buffer status report accounts for the first data. According tothe first embodiment, the pending first scheduling request is cancelledat this point in time, which corresponds to step 504 in FIG. 5.

Step 820 Case b-I).

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report trigger. This second data further,directly or indirectly, triggers a second scheduling request trigger, tosend a scheduling request at the next opportunity.

Step 840 Case b-I).

The user equipment 120 transmits the first data built in the packet dataunit and includes the buffer status report in the packet data unit,which buffer status report was triggered by the first data (mentionedabove) and which buffer status report accounts for the first data butnot the second data.

Step 850 Case b-I).

At this point in time a scheduling request opportunity occurs i.e. afterthe transmission of the data according to case b). Since the secondscheduling request trigger is pending at this point in time, the userequipment 120 sends a scheduling request to the base station 110 at thispoint in time. This is good, since no scheduling request for the seconddata has been transmitted to the user equipment 110 yet. Now, there isno risk for the scheduling request for the second data to be lost!

For case b-II) assume the following steps:

Step 800 Case b-II).

As a response to the scheduling request sent to the base station, theuser equipment 120 receives from the base station an UL grant fortransmission.

Step 820 Case b-II).

New second data arrives in the user equipment buffer. This second datatriggers a buffer status report. This second data further, directly orindirectly via the buffer status report, triggers a second schedulingrequest trigger to send a scheduling request at the next opportunity. Incase a-II), the second data arrives before building the packet dataunit, whereas in case a-I the second data arrived after building thepacket data unit.

Step 830 Case b-II).

During a time period the user equipment 120 builds a packet data unit,such as a MAC PDU, for data to be transmitted in, which data is built inthe packet data unit depending on the priority of the data in userequipments' buffers. The user equipment includes a buffer status reportin the packet data unit (unless all data can fit in but not a bufferstatus report). This packet data unit shall be sent to the base stationat the transmission later on. The buffer status report accounts for thefirst and second data being built in the packed data unit. According tothe first embodiment, the pending first and second scheduling requestsare cancelled at this point in time, which corresponds to step 504 inFIG. 5.

Step 840 Case b-II).

The user equipment 120 transmits the data and the buffer status reportin the packet data unit, which buffer status report accounts for thefirst data and the second data.

Step 850 Case b-II).

At this point in time a scheduling request opportunity occurs i.e. afterthe transmission of the data according to case b). No scheduling requesttrigger is pending since it was cancelled in step 830. This is good inthis case since first and second data are already transmitted oraccounted for in the BSR.

To perform the method steps referred to in FIG. 5 above for handling ascheduling request trigger, the user equipment 120 in one embodiment isconfigured as depicted in FIG. 9.

As mentioned above, the user equipment 120 comprises a buffer 900configured to receive data to be transmitted to the base station 110.

The user equipment 120 further comprises a generating circuit 920configured to generate a scheduling request trigger, which schedulingrequest trigger is pending until it is cancelled, and which generationis triggered directly or indirectly by the arrived data.

The user equipment 120 further comprises a cancelling circuit 930.

According to a first embodiment, the cancelling circuit 930 isconfigured to cancel the pending scheduling request trigger when thedata that triggered the generation of the scheduling request trigger isaccounted for in a buffer status report to be included in a scheduleddata transmission to be transmitted to the base station 110, or when thedata that triggered the generation of the scheduling request is includedin a scheduled data transmission to be transmitted to the base station110, whichever occurs first.

According to a second embodiment, the cancelling circuit 930 isconfigured to cancel the pending scheduling request trigger at any time,but keeps track of what data that has either been accounted for in thebuffer status report to be included in a scheduled data transmission orincluded directly in the scheduled data transmission and what data thathas not been accounted for in any of these two ways.

According to a combined first and second embodiment, the cancellingcircuit 930 is configured to cancel the pending scheduling requesttrigger when the data that triggered the generation of the schedulingrequest trigger is accounted for in a buffer status report to beincluded in a scheduled data transmission to be transmitted to the basestation 110, or when the data that triggered the generation of thescheduling request is included in a scheduled data transmission to betransmitted to the base station 110, whichever occurs first, oralternatively to cancel the pending scheduling request trigger at anytime, but keeping track of what data that has been accounted for in thebuffer status report to be included in a scheduled data transmission andwhat data that has not been accounted for.

According the second embodiment and the combined first and secondembodiment, the user equipment 120 comprises a sending circuit 940configured to, when a next scheduling request opportunity appears, senda scheduling request if and only if the buffer comprises data that hasnot yet been accounted for in any of the two ways mentioned.

According the combined first and second embodiment the sending circuit940 is configured to, when a next scheduling request opportunityappears, send a scheduling request if and only if the buffer comprisesdata that has not yet been accounted for in the buffer status report.

The present mechanism for handling a scheduling request trigger may beimplemented through one or more processors, such as a processor 950 inthe user equipment 120 depicted in FIG. 9, together with computerprogram code for performing the functions of the present disclosure. Theprogram code mentioned above may also be provided as a computer programproduct, for instance in the form of a data carrier carrying computerprogram code for performing the present disclosure when being loadedinto the user equipment 120. One such carrier may be in the form of a CDROM disc. It is however feasible with other data carriers such as amemory stick. The computer program code may furthermore be provided aspure program code on a server and downloaded to the user equipment 120.

FIG. 10 depicts one embodiment of the user equipment 120, includingprocessing circuits operatively associated with transceiver circuits(radiofrequency receiver front-end, transmit modulator/amplifier, etc.),and one or more transmit/receive antennas.

The user equipment 120 is, for example, a mobile terminal or other typeof user equipment configured for operation in a wireless communicationsystem based on the LTE standards.

In any case, the user equipment 120 is configured to implement any ofthe embodiments described herein. For example, the processing circuitsmay comprise one or more baseband processors. In at least oneembodiment, the processing circuits comprise one or moremicroprocessor-based circuits, such as a Digital Signal Processor (DSP)or other digital processor. Further, those skilled in the art willappreciate that the user equipment 120 includes one or more memorycircuits—e.g., non-volatile and volatile—for storing programinstructions, configuration and provisioning data, working data, etc.

In particular, the processing circuits within the user equipment 120include an uplink transmit buffer such as the buffer 900—which may be areserved portion of working memory—for buffering data for uplinktransmission, and an associated controller for implementing all or partof the control and processing described herein and as referred to in thetext above related to FIG. 9. That is, one or more embodiments of thecontroller such as the cancelling circuit 930, are configured to cancela pending scheduling request when the data that triggered the schedulingrequest is included in a buffer status report MAC control element or thedata that triggered the scheduling request is transmitted, whicheveroccurs first as described above. In an LTE context, the user equipment120 can be understood as being configured to cancel a pending schedulingrequest when the buffer status report that triggered the schedulingrequest is canceled.

Alternatively, the user equipment's controller can be configured viahardware, software, or some combination thereof, to track what data hasbeen included or otherwise accounted for in a buffer status report andwhat data has not. Accordingly, when a scheduling request opportunitycomes, the user equipment 120 sends a scheduling request if it has datathat has not yet been accounted for in a buffer status report (thebuffer status report does not have to have been sent; for example, it issufficient if the buffer status report is included in a MAC PDU that hasbeen assembled for transmission.)

Both embodiments 1 and 2 lead to the same behavior, the advantage ofwhich is that it is natural to cancel a pending SR when it has servedits purpose. This is only guaranteed if the pending SR is cancelled whenthe data that triggered it is already accounted for in a buffer statusreport, or the data that triggered it is transmitted. Any other solutionwill lead to ambiguities or unnecessary SRs sent and/or unnecessarygrants.

According to some embodiments, the present disclosure may be referred toas follows. When a scheduling request is triggered, it shall beconsidered as pending until it is cancelled. All pending schedulingrequests shall be cancelled when a MAC PDU is assembled and this PDUincludes a buffer status report which contains buffer status up to (andincluding) the last event that triggered a buffer status report, or whenthe uplink grant can accommodate all pending data available fortransmission.

When using the word “comprise” or “comprising” it shall be interpretedas non-limiting, i.e. meaning “consist at least of”. The word “built” isequal to the word “assembled” in this text.

The present disclosure is not limited to the above described preferredembodiments. Various alternatives, modifications and equivalents may beused. Therefore, the above embodiments should not be taken as limitingthe scope of the present disclosure, which is defined by the claims andtheir legal equivalents.

The invention claimed is:
 1. A method in a user equipment for handling ascheduling request, the method comprising: receiving data to betransmitted to a base station into a buffer of the user equipment;triggering a scheduling request in response to receiving the data, whichscheduling request will remain pending until it is cancelled; andcancelling the pending scheduling request when data in the buffer isaccounted for in any one of the following two ways: a Medium AccessControl (MAC) Packet Data Unit (PDU) is to be transmitted to the basestation, said PDU including a buffer status report which contains bufferstatus up to and including the last event that triggered a buffer statusreport; and an uplink grant has been received which can accommodate allpending data in the buffer that is available for transmission.
 2. Themethod of claim 1, wherein triggering the scheduling request in responseto receiving the data comprises generating a buffer status reporttrigger which in turn triggers the scheduling request.
 3. The method ofclaim 2, wherein canceling the pending scheduling request comprisescanceling the buffer status report trigger, which in turn triggers thecanceling of the pending scheduling request.
 4. The method of claim 1,further comprising: sending the scheduling request to a base stationduring a next scheduling request opportunity if the pending schedulingrequest is still pending during the scheduling request opportunity.
 5. Auser equipment configured to handle a scheduling request, said userequipment comprising: an antenna configured to send and receive wirelesssignals; radio front-end circuitry connected to the antenna and toprocessing circuitry, and configured to condition signals communicatedbetween the antenna and the processing circuitry; and a buffer, whereinthe processing circuitry is configured to: receive data to betransmitted to a base station into the buffer; trigger a schedulingrequest in response to receiving the data, which scheduling request willremain pending until it is cancelled; cancel the pending schedulingrequest when data in the buffer is accounted for in any one of thefollowing two ways: a Medium Access Control (MAC) Packet Data Unit (PDU)is to be transmitted to the base station, said PDU including a bufferstatus report which contains buffer status up to and including the lastevent that triggered a buffer status report; an uplink grant has beenreceived which can accommodate all pending data in the buffer that isavailable for transmission.
 6. The user equipment of claim 5, whereinthe processing circuitry is further configured to trigger the schedulingrequest in response to receiving the data by generating a buffer statusreport trigger, which in turn triggers the scheduling request.
 7. Theuser equipment of claim 6, wherein the processing circuitry is furtherconfigured to cancel the pending scheduling request by cancelling thebuffer status report trigger, which in turn triggers the canceling ofthe pending scheduling request.
 8. The user equipment of claim 5, theprocessing circuitry being further configured to: send the schedulingrequest to a base station during a next scheduling request opportunityif the pending scheduling request is still pending during the schedulingrequest opportunity.
 9. A user equipment configured to handle ascheduling request, said user equipment comprising: an antennaconfigured to send and receive wireless signals; radio front-endcircuitry connected to the antenna and to processing circuitry, andconfigured to condition signals communicated between the antenna and theprocessing circuitry; and a buffer; wherein the processing circuitry isconfigured to: receive data to be transmitted to a base station via ascheduled uplink transmission, and store said data into the buffer; senda scheduling request to the base station when a next scheduling requestopportunity occurs only if the buffer contains data that has both notbeen accounted for in a buffer status report, which reports the size ofsaid buffer to the base station, and will not be included directly in acurrently scheduled uplink transmission.